1. Field of the Invention:
The present invention relates generally to armor piercing projectiles and more particularly to Kinetic energy long rod penetrators that achieve greater penetration.
2. Description of the Prior Art:
The primary function of armor piercing projectiles and long rod (length/diameter.gtoreq.7) penetrators is to penetrate the armor surrounding otherwise vulnerable targets, such as machines or personnel. The penetrating capability and effectiveness of the projectile depends fundamentally on its kinetic energy. The larger the mass and higher the velocity the greater the terminal effects on the target. To attain maximum penetration a variety of parameters must be considered. These parameters include, hardness, stiffness, ductility, strength, density, length and diameter. These parameters are important because they influence the interaction of the penetrator with armored targets.
For example, a trade off exists between the two parameters hardness and ductility. A long rod penetrator may be defeated upon impacting a hardened target by shock induced brittle fracture for high hardness penetrators, termed "breakup", or by excessive plastic flow for tough ductile penetrators, termed "mushrooming". The strength of the penetrator is also important during the launch process and must maintain structural integrity.
The penetration process is also influenced by the density and length of the penetrator. A penetrator that is longer and denser will achieve greater penetration, however, the larger mass imposes a burden of the gun system. It would be most desirable to provide a long rod penetrator which is long and thin (i.e. small diameter) so that the mass burden would be lessened, but this approach results in a penetrator that is structurally unsound.
Until recently, long rod penetrator materials have emphasized homogeneous, high density metals. One variant from this approach is a penetrator that comprises a high density metal core surrounded by a low density, high strength, metal sleeve. This combination tends to balance between the properties of hardness needed for penetration and ductility needed for maintaining structural integrity.
Another variant in penetrator design comprises a high density core with internally reinforcing, low density, high modulus materials such as tungsten or graphite filiments. In either case, the principles used are to increase stiffness and breakage resistance. However, no major successes have been achieved through such approaches.